フリージアの促成栽培における低温処理後の高温遭遇が花芽の形態的変化と開花時の障害発生に及ぼす影響

Abstract

Corms of the freesia 'Blue Heaven' were chilled wet at 10°C for 5 or 6 weeks and the resulting sprouting young plants were immediately exposed to 24°C for 1, 2, or 3 weeks and then to 10°C until they were planted in a plastic house maintained at 5°C or above on 13 Nov. Flower buds, exposed to the high temperature, were prepared and photographed on a scanning electron microscope (SEM). Based on their morphology, the types at flowering were classified into 6 categories. When flower buds were exposed to high temperature during the differentiation of floral primordia, the which formed, varied depending on the developmental stages of flower buds at the start of the high temperature treatment and its duration. These inflorescences were classified as gladiolus bloom or abnormal inflorescence according to the degree of heat injury. The angle between the horizontal and the crossing lines from the base of the first to that of the last floret in an is a practical indicator to measure the degree of gladiolus bloom. Visually normal inflorescence, appeared in plants which received the most severe high temperature treatment. These plants initiated leaves and flower buds after abortion of the pre-differentiated flower buds. Normal and pseudo-normal inflorescences are easily distinguished by the difference in the number of leaves or days from chilling to flowering. Heat injury was less severe if the plants were exposed to high temperatures at a more advanced stage of flower bud development.